AV BET DIN (Heb. אַב בֵּ ית דִּין; "father of the law court"), title of (a) one who presided over a Jewish ecclesiastical court ( *bet din ); (b) the vice president of the Bet Din ha-Gadol ("Supreme Court of Justice") during the Second Temple period. The origin and history of the office are obscure. It is first mentioned in the Mishnah which states that, while one of the (pairs of sages listed in Mishnah Avot 1) was the *nasi (president) of the court, the second held the office of av bet din (Ḥag. 2:2). The Talmud quotes a tradition that even as early a personality as King Saul was the nasi, and his son Jonathan the av bet din (MK 26a). According to some scholars, however, the institution originated at the beginning of the Hasmonean period, when the high priest was the nasi; as he was not usually a great scholar, he needed an assistant to act as the effective president of the Sanhedrin. Indeed, the main duty of the av bet din was evidently to superintend the administration of the court; and it was an official position even in the Lesser Sanhedrin of 23 members found in every city (Ruth R. 2; et al.). A body of regulations affecting the av bet din of the Great (and, according to some opinions, also of a Lesser) Sanhedrin was gradually established by the halakhah. His appointment was to be made orally (TJ, Hor. 3:2 end, 47a). He could not decide a law in the presence of the nasi (Ḥag 16b). The scholars were to rise before him and honor him in the street and on his entry to the Sanhedrin (Kid. 33b; Hor. 13b). Everyone had to rend his garments on the death of an av bet din (MK 26a). At *Usha , it was enacted that if an av bet din was guilty of an offense he was not to be placed under a ban but was to be told: "Preserve your honor and remain at home" (ibid. 17a).
During the geonic period, the term was used to designate the deputy to the principal, *gaon , of the academies of Babylonia and Ereẓ Israel. Usually the av bet din was also the heir-designate of the gaon, generally his son. The deputies are also referred to as rabbenu ha-av ("our rabbi the father"), or simply av ("father").
In the 14th and 15th centuries, the title av bet din was occasionally employed by communities as a synonym for the local rabbi. The title appears more frequently in the communal documents of Poland-Lithuania during the 16th and 17th centuries, and of Russia in the 19th century. Av bet din then designated the principal of the yeshivah who promulgated halakhic rulings and took part in the communal administration; in particular it was used as the title of the district rabbi of a large community. A rabbi who presided over a bet din was termed rav av bet din (abbreviated as ראב״ד ravad). This traditional connotation has remained. In the State of Israel, av bet din also designates the chairman of a civil or a rabbinical court.
A. Buechler, Das Synedrion in Jerusalem… (1902); L. Ginzberg, Perushim ve-Ḥiddushim be-Yerushalmi, 3 (1941), 208–20; H. Tchernowitz, Toledot ha-Halakhah, 4 (1950), 262–76; Alon, Meḥkarim, 2 (19582), 22–23, no. 37; H. Mantel, Studies in the History of the Sanhedrin (1961), 102–29, contains detailed bibliography; ET, 1 (1955), 10–11; Assaf, Ge'onim, 44; H.H. Ben-Sasson, Hagut ve-Hanhagah (1959), index; Weiss, in: JJS, 1 (1948), 172–7.
Source: Encyclopaedia Judaica. © 2008 The Gale Group. All Rights Reserved.